Instructions on how to use these diagrams can be found here: https://archive.org/details/instructionbook00diam
The 1:1 scale is at 30 inches, the easiest way to work with these is to take a strip of paper the length of your bust or waist, depending on what the specific diagram tells you to use, then split it into 30 segments and go from there.

these patterns are intended to be done with scale rulers based on imperial measurements. meaning its based off inches so divisions of 8.if you can math you should be able to find the correct scale. if you cant ... i would suggest either finding someone who can or just drafting it out with a standard ruler and making adjustments from there.

Contains to-scale patterns of fashionable late 19th century clothing: puffed sleeves, narrow waists, A-line skirts. Mostly women's dresses, but it has some children's clothing and a few men's patterns as well.

I haven't read the entire book, but an initial skim didn't reveal any instructions on how to size the patterns. There are numbers printed on the patterns that appear to be measurements or scale indicators, but I haven't figured them out yet.

The patterns are inspiring and would be sufficiently informative for someone with more pattern drafting knowledge.